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Abstract  

A time-saving and accurate technique for determining226Ra in groundwater and soil was examined, using high-resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS). The technique was applied to the determination of226Ra in groundwater and soil samples and compared with the conventional liquid scintillation counting method. This technique was capable of completing226Ra counting within 3 minutes, without the in-growth period to allow radon and its progeny to achieve secular equilibrium with the parent226Ra. The detection limits of HR-ICP-MS for226Ra in groundwater and soil were 0.19 mBq·1−1 and 0.75 Bq·kg−1, respectively, which were about 10 times lower than that of the liquid scintillation counter. The results obtained from HR-ICP-MS in groundwater and soil were in accordance with those of LSC within a relative error of about 13%.

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Abstract  

The formation of precipitates by hydrazine was experimentally examined in the simulated high level liquid waste (HLLW), which was composed of 9 elements (Nd, Fe, Ni, Mo, Zr, Pd, Ru, Cs, Sr). Palladium was precipitated over 90% above 0.05M of hydrazine concentration and at 2M HNO3, while all of the other elements were hardly precipitated. The elements of Pd and Zr were precipitated 93% and 70% in the simulated solution in which the concentrations of Zr and Mo were decreased from 0.069M to 3.45·10–3M and 6.9·10–3M, respectively, and the acid concentration was decreased to about 0.5M after denitration. In a Pd solution of 0.5M and 2M HNO3, the precipitation yield of Pd increased with hydrazine concentration and reached over 98% at 0.1M. The precipitation yield of Pd at 0.5M HNO3 was higher than at 2M HNO3. The Pd precipitate, formed by adding hydrazine to an acidified solution, was an amorphous compound consisting of Pd, hydrazine, nitrate and hydrate.

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Abstract  

The removal of Cs and Re (as a surrogate for Tc) by selective precipitation from the simulated fission products which were co-dissolved with uranium during the oxidative dissolution of spent fuel in a Na2CO3–H2O2 solution was investigated in this study. The precipitations of Cs and Re were examined by introducing sodium tetraphenylborate (NaTPB) and tetraphenylohosponium chloride (TPPCl), respectively. The precipitation of Cs by NaTPB and that of Re by TPPCl each took place within 5 min, and an increase in temperature up to 50 °C and a stirring speed up to 1000 rpm hardly affected their precipitation rates. The most important factor in the precipitation with NaTPB and TPPCl was found to be a pH of the solution after precipitation. Since Mo tends to co-precipitate with Cs or Re at a lower pH, an effective precipitation with NaTPB and TPPCl was done at pH of above 9 without the co-precipitation of Mo. More than 99% of Cs and Re were precipitated when the initial concentration ratio of NaTPB to Cs was above 1 and when that of TPPCl to Re was above 1. The precipitation of Cs and Re was never affected by the concentration of Na2CO3 and H2O2, even though they were raised up to 1.5 and 1.0 M, respectively. Precipitation yields of Cs and Re in a Na2CO3–H2O2 solution were found to be dependent on the concentration ratios of [NaTBP]/[Cs] and [TPPCl]/[Re].

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Abstract  

The applicability of vitrification technology to treat radioactive incineration ash was studied, especially in terms of leaching characteristics, by using several glassy waste forms which are fabricated with simulated incineration ash and base-glass at different mixing ratios. The ISO leaching test has been conducted for 820 days. Two semi-empirical models were applied to find out the dominant leaching mechanism of glass elements. Dissolution associated with diffusion was the dominant leaching mechanism and the elemental leaching characteristic depended upon its solubility in water. A theoretical leaching prediction model was applied to observe the long-term leaching behavior of major glass elements and surrogate nuclides. Diffusion coefficients and dissolution rate constants, the main parameters in the long-term prediction model, of glass elements and surrogates were obtained using short- and long-term experimental data. The model was found to be useful in predicting the long-term behavior of such elements in order to assess the stability of glassy waste forms.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Dong-Yong Chung
,
Eung-Ho Kim
,
Young-Joon Shin
,
Jae-Hyung Yoo
,
Cheong-Song Choi
, and
Jong-Duk Kim

Abstract  

The decomposition rate of oxalate by hydrogen peroxide has been investigated by a KMnO4 titration method. The rate equation for decomposition of hydrogen peroxide in the aqueous phase is 1n([H2O2]/[H2O2]0)=–k1·t, where k1=0.2, for [H+]<2M, k1=0.2+0.34([H+]–2), for [H+]>2M. As the acidity increases over 2M, an acid catalysis effect appeard. The new rate equation proposed for the decomposition of oxalate by hydrogen peroxide is

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$- \frac{d}{{dt}}X_{[OX]} = k_2 [H_2 O_2 ]_0 (1 - X_{[OX]} )(e^{ - k_1 t} - \frac{{[OX]_0 }}{{[H_2 O_2 ]_0 }}X_{[OX]} )$$ \end{document}
The rate constant for decomposition of oxalate, k2, increased with nitric acid concentration and the effect of hydrogen ion concentration was expressed as k2=a[H+]n, where the values fora andn were a=1.54, n=0.3 at [H+]<2M, a=0.31, n=2.5 at [H+]>2M, respectively.

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Acta Veterinaria Hungarica
Authors:
Hye Park
,
Min Hong
,
Sun Hwang
,
Young Park
,
Ka Kwon
,
Jang Yoon
,
Sook Shin
,
Jae Kim
, and
Yong Park

Pseudomonas aeruginosa is one of the causative pathogens of bovine mastitis. Most P. aeruginosa strains possess the type III secretion system (TTSS), which may increase somatic cell counts (SCCs) in milk from mastitis-affected cows. Moreover, most of P. aeruginosa cells can form biofilms, thereby reducing antibiotic efficacy. In this study, the presence and effect of TTSS-related genotypes on increase of SCCs among 122 P. aeruginosa isolates obtained from raw milk samples from mastitis-affected cows and their antibiotic susceptibility at planktonic and biofilm status were investigated. Based on the presence of TTSS-related genes a total of 82.7% of the isolates were found to harbour exoU and/or exoS genes, including the invasive (exoU-/exoS+, 69.4%), cytotoxic (exoU+/exoS-, 8.3%) and cytotoxic/invasive strains (exoU+/ exoS+, 5.0%). Milk containing exoS-positive isolates had higher SCCs than those containing exoS-negative isolates. The majority of isolates showed gentamicin, amikacin, meropenem and ciprofloxacin susceptibility at planktonic status. However, the susceptibility was decreased at the biofilm status. Based on minimum biofilm eradication concentration (MBEC)/minimum inhibitory concentration (MIC) ratios, the range of change in antibiotic susceptibility varied widely depending on the antibiotics (from ≥ 3.1-fold to ≥ 475.0-fold). In conclusion, most P. aeruginosa isolates studied here had a genotype related to increase in SCCs. The efficiency of antibiotic therapy against P. aeruginosa-related bovine mastitis could be improved by analysing both the MBEC and the MIC of isolates.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Dong-Yong Chung
,
Heui-Seung Seo
,
Jae-Won Lee
,
Han-Beom Yang
,
Eil-Hee Lee
, and
Kwang-Wook Kim

Abstract  

A feasibility and basic study to find a possibility to develop such a process for recovering U alone from spent fuel by using the methods of an oxidative leaching and a precipitation of U in high alkaline carbonate media was newly suggested with the characteristics of a highly enhanced proliferation-resistance and more environmental friendliness. This study has focused on the examination of an oxidative leaching of uranium from SIMFUEL powders contained 16 elements (U, Ce, Gd, La, Nd, Pr, Sm, Eu, Y, Mo, Pd, Ru, Zr, Ba, Sr, and Te) using a Na2CO3 solution with hydrogen peroxide. U3O8 was dissolved more rapidly than UO2 in a carbonate solution. However, in the presence of H2O2, we can find out that the leaching rates of the reduced SIMFUEL powder are faster than the oxidized SIMFUEL powder. In carbonate solutions with hydrogen peroxide, uranium oxides were dissolved in the form of uranyl peroxo-carbonato complexes. UO2(O2) x (CO3) y 2−2x−2y , where x/y has 1/2, 2/1.

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Acta Veterinaria Hungarica
Authors:
Sung Jae Kim
,
Van Giap Nguyen
,
Cheong Ung Kim
,
Bong Kyun Park
,
Thi-My Le Huynh
,
Sook Shin
,
Woo Kyung Jung
,
Yong Ho Park
, and
Hee Chun Chung

Abstract

Porcine epidemic diarrhoea virus (PEDV) is one of the major pathogens causing acute enteritis, which is characterised by vomiting and watery diarrhoea and commonly leads to high rates of mortality and morbidity in suckling piglets. Chitosan has been regarded as a promising natural disinfectant. In this study, the disinfectant effect and mammalian-cell toxicity of chitosan were evaluated against PEDV using Vero cells. A 0.01% solution of chitosan was determined to be an effective disinfectant. In addition, no evidence of toxicity was observed during the cell toxicity test; on the contrary, chitosan promoted cell proliferation. In conclusion, chitosan is a promising candidate for an effective and safe disinfectant against PEDV as well as other coronaviruses.

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